The movie starts with William Tracy as Dodo Doubleday, proving his incredible memory on a radio talk show.
He joins the army after memorizing the regulations, which gets him quickly promoted to sergeant.
His youth and inexperience bothers the other NCO's, namely Sgt. Ames (Joe Sawyer), who spends the movie trying to get Doubleday in trouble.
But because of is inherent honesty and cleverness, Doubleday is able to bumble through the requisite series of mishaps and inspire loyalty in what looked to be a renegade unit.
You can find the third film of this series of four here